1. Field of the Invention
This invention relates generally to an audio system for a computer and, more particularly, to an audio power management system for eliminating noise generated when portions of the computer are powered up or powered down during power management operation.
2. Description of the Related Art
The rapid acceptance of computer technology by corporations as well as consumers has led to the widespread use of computers. The daily operations of these computers in aggregate consume a significant amount of electrical energy. Thus, efficient power management of each computer is important for many reasons, including the conservation of energy and the protection of the environment.
Many of today's desktop personal computers offer power-down capability to conserve energy. In such a system, the computer automatically powers down the disk drive and removes power from certain electronics when the computer has been idle for a certain period of time. Upon detecting keyboard activities or other predefined activating events, the computer "wakes-up" automatically by applying power to turn on the electronic subsystems.
In a separate trend, audio capabilities of computers are increasing. Multimedia is becoming very prevalent and some of the audio subsystems are becoming more sophisticated. It is common to provide separate audio amplifiers in the computer to drive either a high quality internal speaker or external speakers and headphones.
However, a problem occurs with the audio subsystems. Whenever the amplifiers are turned on or off, a pop or snap occurs. This has been considered acceptable when the entire computer system is turned on or off. But the merging of power conservation features with the audio subsystem creates a greater problem. During power conservation operation, the audio amplifiers will be powered on and off. This will result in pops and snaps, as at system turn on or off, but now the pops and snaps will not be associated with the larger event of system activation. Indeed, the pops and snaps will generally occur when the computer is not being used. This seemingly random popping and snapping thus is a problem which must be solved. Further, the number of digital pins to control this activity may be limited, rendering the control even more difficult.